Objectives: As people age and the incidence of dementia increases, studies of cognitive function continue to be of importance. Ascertaining cognitive data through different mechanisms is necessary to address missing data concerns.
Methods: The Dementia Questionnaire (DQ), which utilizes proxy-based assessments, is a potential tool to determine cognitive status in participants no longer being followed per traditional study protocol. The DQ is currently being used in the Supplemental Case Ascertainment Protocol (SCAP), which is being conducted in an ongoing study of postmenopausal women as part of the Women's Health Initiative Memory Study (WHIMS).
Results: Ninety-four percent of the 1260 SCAP participants were eligible because of being deceased. Those who are SCAP eligible were older, were less likely to be a minority, and were more likely to have hypertension, diabetes, and prior history of cardiovascular disease (CVD) as well as being a past or current smoker. SCAP added 109 cases of probable dementia to WHIMS. Risk factor relationships were modified upon inclusion of the SCAP cases including an attenuation of a hormone therapy effect and discovery of a hypertension effect.
Conclusions: Augmenting clinic-based cases with proxy-based assessments is feasible and leads to increased incident cases of dementia. When planning future clinical trials, it may be of study benefit to include a protocol of proxy-based assessments, develop strong relationships with proxies early on in the study, and attempt to maintain this relationship throughout the lifespan of the trial.
Trial registration: ClinicalTrials.gov NCT01124773.
Keywords: clinical trials; cognitive aging; missing data.
© 2019 John Wiley & Sons, Ltd.